Habitat

Akodon montensis is found in both temperate and tropical habitats. Within these habitats it occupies evergreen, semi-deciduous, and riparian gallery forests. It is also found in grassland and coastal biomes and in open areas. Furthermore, it occurs in agricultural fields, gardens, and young secondary growth. Generally, the species prefers areas with ground cover and leaf litter. Akodon montensis can be found at elevations of 800 m, but is more common at elevations of 900 m or higher. (Couto and Talamoni, 2005; Couto and Talamoni, 2005; Jordao, et al., 2010; Pardinas, et al., 2008)

Physical Description

Akodon montensis is a small rodent with a heavy body that is often described as closely resembling a vole. Young differ from adults only in size, and males (45 g) are slightly larger than females (40 g). Adult mass ranges from 19 to 57 g, with a mean of 42 g. Total length of Akodon montensis ranges from 90 to 136 mm, with hind feet ranging from 17 to 28 mm long, ears ranging from 11 to 21 mm long, and tails ranging from 32 to 98 mm long. Although its basal metabolic rate is unknown, the basal metabolic rate for other members of Akodon is typically around 46 mL of oxygen per hour. Dorsal pelage of A. montensis is auburn and fades to lighter tan on the sides. The venter is either reddish grey or reddish tan with a slight orange hew. It has tan feet and a sparsely haired tail. Akodon montensis looks similar to Akodon cursor, however, A. montensis is smaller than A. cursor. (Bozinovic, 1992; Goncalves, et al., 2007; Redford and Eisenberg, 1989; Wienke and Yahnke, 2007)

Reproduction

Reproductive behavior of Akodon montensis has not been extensively studied, and the mating system that best characterizes this species is currently unknown.

Reproductive efforts of male Akodon montensis occurs via a four-stage process. First, recrudescence of spermatogenesis occurs, followed by the act of mating. These two stages take place between October and February (the wet season). The third stage, regression of activity and spermatogenesis, and the fourth stage, rest, take place from March to July (the dry season). If the immediate environment and weather are favorable, mating can take place year round. Typically, females have two litters but may have more if environmental conditions are favorable. Litter size ranges from 3 to 10 offspring, with an average litter size of 5. On average, gestation lasts 23 days, and offspring are typically weaned within 15 days. Males achieve sexual maturity in 32 to 37 days while females achieve sexual maturity between 35 and 91 days. Sexual maturity is most often reached between October and March. No information on birth mass is available, but average birth mass of other members of Akodon (e.g., Akodon lindberghi and Akodon azarae) ranges from 1.97 g to 3.10 g. No information is available concerning time to independence. Reproductively active and fertile females can be found in the wild with XY chromosomes. (Couto and Talamoni, 2005; De Conto and Cerqueira, 2007; Nowalk, 1991; Suarez, et al., 2004; Wienke and Yahnke, 2007)

Information on parental investment specific to Akodon montensis is not available. However, in most mammals care of the young (e.g., provisioning and protecting) is performed by the mother from the time of fertilization until independence. (Dewey, 2011; Higdon, 2004)

Lifespan/Longevity

No specific information is available pertaining to the lifespan of Akodon montensis, aside from observations that they have a short life expectancy and quick population turnover . One member of Akodon, Akodon azarae, has a maximum lifespan of 18 months but typically lives one year or less. (Higdon, 2004; Kittlein, 2008; Wienke and Yahnke, 2007)

Home Range

The home range of Akodon montensis is relatively small, with individuals occupying 36 m^2 on average. Home ranges never exceed 100 m^2 and do not vary in size between genders or seasons. (Jordao, et al., 2010; Wienke and Yahnke, 2007)

Communication and Perception

There is no information available on intraspecific communication in Akodon montensis. Its close relative, Akodon cursor uses olfactory cues to inform conspecifics about reproductive availability and territorial boundaries. (Higdon, 2004; Higdon, 2004)

Economic Importance for Humans: Positive

There are no known positive effects of Akodon montensis on humans. However, it may help control insect pest populations throughout its native range.

Economic Importance for Humans: Negative

Akodon montensis poses two main problems for humans. First, it is a known vector for hantaviruses. When transmitted to humans this virus can cause hantavirus pulmonary syndrome which can be fatal. Secondly, some members of the genus Akodon have a significant impact on agriculture by foraging on crops (e.g., rice, maize, peanuts, and cereal crops), resulting in a 10% to 90% decrease in crop yield. (Goodin, et al., 2009; Stenseth, et al., 2003)

Negative Impacts

injures humans

carries human disease

crop pest

Conservation Status

Although Akodon montensis is thought to be decreasing in abundance, it is currently listed as a species of least concern by the IUCN Red List of Threatened Species. (Pardinas, et al., 2008)

Other Comments

Akodon montensis was formerly considered a subspecies of Akodon cursor. It has recently been promoted to species level based on several factors, including occupying a different elevational habitat then Akodon cursor and having a different karyotype (2n=24 for Akodon montensis, 2n=14/15 for Akodon cursor). Akodon montensis does not have a gall bladder but Akodon cursor does. Due to this recent change in classification, it is often difficult to determine if the study results apply to Akodon cursor or Akodon montensis. (Wienke and Yahnke, 2007)

Contributors

Glossary

living in the southern part of the New World. In other words, Central and South America.

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

Goncalves, P., P. Myers, J. Vilela, J. De Oliveira. 2007. Systematics of Species of the Genus Akodon (Rodentia: Sigmondontinae) in Southeastern Brazil and implications for the Biogeography of the Campos De Altitude. Ann Arbor, MI: Museums of Zoology, University of Michigan.

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This material is based upon work supported by the
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Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.